In a conventional vapor compression system, vapor refrigerant is compressed in the compressor, where its temperature is raised above the temperature of the cooling medium used at the condenser. A mixture of vapor and liquid refrigerant then enters the condenser where heat is extracted, and the refrigerant changes to a liquid. The liquid refrigerant enters the thermal expansion valve, which controls the quantity of liquid refrigerant passing to the evaporator coils. Finally, the liquid refrigerant enters the evaporator and evaporates. Heat from the ambient atmosphere, for example, in a vehicle passenger compartment, is rejected to the refrigerant in the evaporator where it is absorbed as the latent heat of vaporization as the refrigerant evaporates. The now vaporized refrigerant is then directed to the compressor to be recycled through the system.
Some vapor compression systems include a receiver which is intended to perform some or all of the following functions: filtration and/or dehydration of the refrigerant, compensation for variations in its volume, and separation of the vapor and liquid phases of the refrigerant. Typically, an inlet pipe is coupled between an upstream section of the condenser and an inlet aperture of the receiver for carrying the vapor and liquid phases of the refrigerant to the receiver. An outlet pipe is coupled between an outlet aperture of the receiver and a downstream section of the condenser header for returning the liquid phase of the refrigerant to the downstream section. Interposing the receiver between upstream and downstream sections of the condenser ensures the fluid in the downstream section circulates only in the liquid state. The downstream section, or sub-cooler section, of the condenser sub-cools the liquid refrigerant to a point below the temperature at which the liquid changes to a gas. The sub-cooled liquid phase refrigerant quality is low and its enthalpy is also low which increases the evaporator's ability to absorb heat as the refrigerant evaporates, thus improving the efficiency of the vapor compression system.
Condenser systems used in vehicle air conditioning systems are typically manufactured by first assembling brazing clad condenser components, then passing the assembled components through a brazing furnace to braze, or fuse, the components together. Generally, one or more brackets and fasteners are used to mount the receiver, inlet pipe, and outlet pipe to a header of the condenser. The bracket or brackets may also be coupled to the header during the brazing process. The receiver is then coupled to a condenser header during a post-braze assembly process.
Post-braze assembly is typically performed manually, thus resulting in undesirably high labor costs. In addition, a high number of discrete components burdens those responsible for inventory control, increases the likelihood that the condenser system may be incorrectly assembled, and increases the potential for damaging the condenser system and/or receiver during post-braze assembly.
It is known to utilize desiccants to remove moisture from the refrigerant, filters to remove particulates, tracer dyes for leak detection, and the like in receivers. These additional enhancements are inserted into the receiver during post-braze assembly. The problems of undesirably high labor costs, inventory control, incorrect assembly, and potential for damage are exacerbated in receivers that utilize these additional discrete elements.
In order to mitigate some of the problems associated with post-braze assembly, some prior art receivers are coupled to the condenser header during the brazing process, thus yielding an integrated condenser with receiver. Unfortunately, difficulties have arisen in the development of desiccants, desiccant bags, filter materials, and dye materials that can withstand the heat of the brazing process. Consequently, many of these receivers do not include those enhancements.
Alternatively, some prior art integrated receivers require a portion of the receiver to be removable for installation of the desiccant and/or filter after the condenser with integrated receiver is brazed. After the desiccant and/or filter is installed in the receiver dryer, the receiver can then be permanently closed by welding a cap on one end. Alternatively, additional fasteners can be used for post-brazing assembly, as well as O-rings for sealing the receiver. Again, problems arise with a high number of discrete components, undesirably high labor costs, and so forth.
Regardless of the type of receiver employed (whether it's coupled to the condenser header during post-braze assembly or during the brazing process), it is desirable to have the capability of replacing desiccant bags, filters, and/or dyes in the receiver during routine condenser maintenance. Unfortunately, once installed into an automobile it is often difficult and even impossible to access the receiver due to the vehicle envelope and interference of surrounding components.
Thus, what is needed is a receiver for a condenser that calls for limited post-braze assembly and is readily serviceable. In addition, what is needed is an apparatus that combines multiple features such as, drying, filtering, and leak detection for ready installation into the receiver.